This disclosure relates generally to electric vehicle supply equipment (EVSE) installations for charging an electric vehicle (EV). More particularly, this disclosure relates to methods and equipment for sharing and allocating power among multiple EVSE units.
The disclosure addresses an EVSE installation wherein two EVSE units share a common power line and a circuit breaker. In one disclosed application, the disclosure illustrates how the power utilized by each EVSE is effectively and efficiently controlled when two EVSE units are sharing a common circuit breaker, such as, for example, a 40 A circuit breaker. Pursuant to standard practice, the continuous power supplied by the breaker is 80% of its rated capacity—which is 32 A for a 40 A circuit breaker.
The ideal situation is for each Level 2 (30 A) EVSE to have its own dedicated 40 A circuit breaker. This is not always possible or practical for existing installations where there is already an existing EVSE and it is desired to add another EVSE to increase the number of charging parking spaces or situations wherein vehicles may be parked at the EVSE station for an extended time period. In many cases, one EV being charged may not be utilizing the full 30 A charge current available, and the remaining charge capacity could be utilized by a second EVSE to charge an additional EV.